/// <summary>
/// Updates the page.
/// </summary>
/// <param name="subPageNumber">The sub page number.</param>
/// <param name="pageData">The page data.</param>
/// <returns></returns>
private void UpdatePage(int subPageNumber, byte[] pageData)
{
if (subPageNumber < 0 || subPageNumber > _numberOfSubPages)
{
return;
}
IntPtr pagePtr = _pageCache[subPageNumber];
unsafe
{
byte *ptr = (byte *)pagePtr.ToPointer();
bool isSet = Hamming.IsEraseBitSet(0, ref pageData);
for (int row = 0; row < 31; row++)
{
int off = row * 42;
if (row != 0)
{
if (pageData[off] == 32 && isSet)
{
for (int col = 0; col < 42; col++)
{
if (ptr[off + col] != 32 && pageData[off + col] == 32)
{
ptr[off + col] = 32;
}
}
continue;
}
}
off = row * 42;
int rowNr = Hamming.GetPacketNumber(off, ref pageData);
if (rowNr < 0)
{
continue;
}
for (int col = 0; col < 42; col++)
{
byte newData = pageData[off + col];
if (rowNr != 0)
{
if (ptr[off + col] != newData)
{
if (rowNr >= 1 && rowNr <= 24)
{
if (col >= 2)
{
if (OddParity.IsCorrect(newData))
{
ptr[off + col] = newData;
}
}
else if (Hamming.Decode[newData] != 0xff)
{
//bytes 0-1 = row/column, hamming 8/4 coded
ptr[off + col] = newData;
}
}
else
{
//rows 25,26,27
ptr[off + col] = newData;
}
}
}
else
{
//row 0
ptr[off + col] = newData;
}
}
}
}
return;
}
private bool PageDiffers(byte[] pageData, int subPageNumber)
{
if (subPageNumber < 0 || subPageNumber > _numberOfSubPages)
{
return(false);
}
IntPtr pagePtr = _pageCache[subPageNumber];
if (pagePtr == IntPtr.Zero)
{
return(false);
}
unsafe
{
byte *ptr = (byte *)pagePtr.ToPointer();
bool isSet = Hamming.IsEraseBitSet(0, ref pageData);
for (int row = 0; row < 31; row++)
{
int off = row * 42;
if (row != 0)
{
if (pageData[off] == 32 && isSet)
{
for (int col = 0; col < 42; col++)
{
if (ptr[off + col] != 32 && pageData[off + col] == 32)
{
return(true);
}
}
continue;
}
}
off = row * 42;
int rowNr = Hamming.GetPacketNumber(off, ref pageData);
if (rowNr < 0)
{
continue;
}
for (int col = 0; col < 42; col++)
{
byte newData = pageData[off + col];
if (rowNr != 0)
{
if (ptr[off + col] != newData)
{
if (rowNr >= 1 && rowNr <= 24)
{
if (col >= 2)
{
if (OddParity.IsCorrect(newData))
{
// Trace.WriteLine(String.Format("2) {0:X}/{1} r:{2} c:{3} {4} {5:X}!={6:X}", _pageNumber, subPageNumber, row, col, _clearSubPage[subPageNumber], ptr[off + col], pageData[off + col]));
return(true);
}
}
else if (Hamming.Decode[newData] != 0xff)
{
//bytes 0-1 = row/column, hamming 8/4 coded
//Trace.WriteLine(String.Format("3) {0:X}/{1} r:{2} c:{3} {4} {5:X}!={6:X}", _pageNumber, subPageNumber, row, col, _clearSubPage[subPageNumber], ptr[off + col], pageData[off + col]));
return(true);
}
}
else
{
//rows 25,26,27
//Trace.WriteLine(String.Format("4) {0:X}/{1} r:{2} c:{3} {4} {5:X}!={6:X}", _pageNumber, subPageNumber, row, col, _clearSubPage[subPageNumber], ptr[off + col], pageData[off + col]));
return(true);
}
}
}
}
}
}
return(false);
}
